Conditions For Setting DTC

No related DTCs.
Engine coolant temperature is 140°F (60°C) or more.
Engine is operating in closed loop.
Engine has been running at least one minute.
Canister purge duty cycle is 10 percent or more.
Engine speed is between 1500 and 3000 RPM.
Mass air flow is between 18 and 42 g/s.
Above conditions are present for a 3 second monitoring period.
Ninety seconds after closed loop operation has been enabled, Bank 1 HO2S No. 1 transition ratio between lean-to-rich and rich-to-lean is less than 0.44 or more than 3.8.